In the course of her research, Dweck has repeatedly found that a person’s performance depends in large part on which of the two beliefs he espouses. If you believe yourself to be capable of improvement, believe that your mind can learn, can become better, can overcome setbacks, you are setting yourself—and your brain—up for exactly that path. And if you don’t? You may find yourself living in a kind of self-fulfilling prophesy, where you prove those elementary school teachers right simply by believing that what they say is the way things are—instead of, like Mischel and Dweck, challenging the very assumption at its core.